阅读说明：本技术 一种无碳不烧镁铝砖及其制备方法 (Carbon-free unburned magnesia-alumina brick and preparation method thereof ) 是由 吕仁祥 纪怀杰 刘在春 于 2020-06-04 设计创作，主要内容包括：本发明公开了一种无碳不烧镁铝砖及其制备方法,主要涉及耐火新材料技术领域,包括,电熔镁砂83-95份；氧化铝粉3-10份；金属铝粉1-4份；酚醛树脂1-3份,镁铝砖的骨料为大粒度的电熔镁砂,细粉为MgO细粉、Al-(2)O-(3)粉、金属Al粉等材料组合,在高温使用过程中细粉中的MgO、Al-(2)O-(3)原位固相合成尖晶石,尖晶石的永久膨胀率和尖晶石的稳定性弥补了镁砂颗粒由于膨胀导致的剥落现象,在工作层表面形成了尖晶石层,使产品在高温使用过程中具有较好的耐剥落和抗渣蚀性能,添加的金属铝粉或铝镁合金粉起到抗氧化作用。(The invention discloses a carbon-free unburned magnesia-alumina brick and a preparation method thereof, which mainly relate to the technical field of new refractory materials and comprise 83-95 parts of fused magnesia; 3-10 parts of alumina powder; 1-4 parts of metal aluminum powder; 1-3 parts of phenolic resin, wherein the aggregate of the magnesia-alumina brick is fused magnesia with large granularity, and the fine powder is MgO fine powder and Al fine powder 2 O 3 Powder, metal Al powder and other material composition, and MgO and Al in the fine powder during high temperature use 2 O 3 The spinel is synthesized in situ in a solid phase manner, the permanent expansion rate of the spinel and the stability of the spinel compensate the peeling phenomenon of magnesia particles caused by expansion, a spinel layer is formed on the surface of a working layer, so that the product has better peeling resistance and slag corrosion resistance in the high-temperature use process, and the added metal aluminum powder or aluminum magnesium alloy powder has an antioxidation effect.)

1. The carbon-free unburned magnesia-alumina brick is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

83-95 parts of fused magnesia;

3-10 parts of alumina powder;

1-4 parts of metal aluminum powder;

1-3 parts of phenolic resin.

2. The carbon-free unburned magnesia-alumina brick according to claim 1, wherein: the electric melting magnesite is one or more of 96%, 97% and 98% of magnesium content.

3. The carbon-free unburned magnesia-alumina brick according to claim 1 or 2, wherein: the particle size of the fused magnesite is one or a mixture of more than 0.088mm, 0.088-1mm, 1-3mm and 3-5 mm.

4. The carbon-free unburned magnesia-alumina brick according to claim 1, wherein: the alumina powder is one or more of high-temperature alpha alumina micro powder, corundum fine powder and high-quality alumina fine powder.

5. The carbon-free unburned magnesia-alumina brick according to claim 4, wherein: the granularity of the high-temperature alpha alumina micro powder is one or a mixture of more than one of 1 micron, 3 microns and 5 microns, the granularity of the corundum fine powder is less than 0.074mm, and the granularity of the high-quality bauxite fine powder is less than 0.074 mm.

6. The carbon-free unburned magnesia-alumina brick according to claim 1, wherein: the metal aluminum powder is one or the combination of two of aluminum powder or aluminum magnesium alloy powder with the granularity of less than 0.074mm and the metal activity of more than 98 percent.

7. The carbon-free unburned magnesia-alumina brick according to claim 1, wherein: the phenolic resin is thermoplastic phenolic resin for refractory materials.

8. The method for preparing the carbon-free unburned magnesia-alumina brick according to claim 1, characterized in that: comprises the following steps of (a) carrying out,

accurately metering the raw materials in proportion, and premixing the fine powder, alumina powder and metal aluminum powder in the fused magnesia to ensure that the raw materials with small amount and fine granularity can be uniformly distributed.

Secondly, adding the particles of the fused magnesia and the premix into a pug mixer, mixing for 2-3 minutes, adding phenolic resin, and continuing mixing for 8-10 minutes;

thirdly, the pug after mixing is beaten and formed on a brick press with proper mould and proper pressure to produce the required brick shape, and the brick shape is placed on a brick vehicle;

and (IV) pushing the formed brick blank vehicle into a tunnel drying kiln for drying for 24 hours, wherein the drying temperature is gradually pushed from the low-temperature region of the kiln inlet to the high-temperature region in the middle, then to the low-temperature region of the kiln outlet, and finally after 24 hours, the brick blank vehicle is taken out of the kiln, and the highest control temperature is 220 +/-10 ℃.

Technical Field

The invention mainly relates to the technical field of new refractory materials, in particular to a carbon-free unburned magnesia-alumina brick and a preparation method thereof.

Background

At present, when steel grades such as low-carbon and ultra-low-carbon stainless steel or refined steel are produced, the refractory materials for the lining are basically sintered magnesia-chrome bricks at present, but hexavalent chromium in the magnesia-chrome bricks can cause environmental pollution in the production process and the use process and is harmful to human bodies, carbon-containing refractory materials and the magnesia-chrome bricks are limited to a certain extent, the magnesia-chrome refractory materials are limited in the application all over the world, and the magnesia-chrome bricks are easy to peel off in the use of a refining slag-covering line; carbon in the carbon-containing refractory material has an influence on the carbon content of molten steel, so that the refractory material of the refining furnace has a trend of being free of chromium and is more and more emphasized.

Disclosure of Invention

In view of the defects and shortcomings in the prior art, the invention aims to provide a carbon-free unburned magnesia-alumina brick and a preparation method thereof.

In order to solve the technical problems, the invention adopts the following technical scheme: a carbon-free unburned magnesia-alumina brick comprises,

83-95 parts of fused magnesia;

3-10 parts of alumina powder;

1-4 parts of metal aluminum powder;

1-3 parts of phenolic resin.

As a further improvement of the invention, the fused magnesite is one or more of 96%, 97% and 98% of magnesium content.

As a further improvement of the invention, the particle size of the fused magnesia is one or a mixture of particle sizes of less than 0.088mm, 0.088-1mm, 1-3mm and 3-5 mm.

As a further improvement of the invention, the alumina powder is one or more of high-temperature alpha alumina micro powder, corundum fine powder and high-quality alumina fine powder.

As a further improvement of the invention, the high-temperature alpha alumina micro powder has one or more of the mixed particle sizes of 1 micron, 3 microns and 5 microns, the particle size of the corundum fine powder is less than 0.074mm, and the particle size of the high-quality alumina fine powder is less than 0.074 mm.

As a further improvement of the invention, the metal aluminum powder is one or a combination of two of aluminum powder or aluminum magnesium alloy powder with the particle size of less than 0.074mm and the metal activity of more than 98 percent.

As a further improvement of the invention, the phenolic resin is a thermoplastic phenolic resin for refractory materials.

A preparation method of a carbon-free unburned magnesia-alumina brick comprises the following steps,

accurately metering the raw materials in proportion, and premixing the fine powder, alumina powder and metal aluminum powder in the fused magnesia to ensure that the raw materials with small amount and fine granularity can be uniformly distributed.

Secondly, adding the particles of the fused magnesia and the premix into a pug mixer, mixing for 2-3 minutes, adding phenolic resin, and continuing mixing for 8-10 minutes;

thirdly, the pug after mixing is beaten and formed on a brick press with proper mould and proper pressure to produce the required brick shape, and the brick shape is placed on a brick vehicle;

and (IV) pushing the formed brick blank vehicle into a tunnel drying kiln for drying for 24 hours, wherein the drying temperature is gradually pushed from the low-temperature region of the kiln inlet to the high-temperature region in the middle, then to the low-temperature region of the kiln outlet, and finally after 24 hours, the brick blank vehicle is taken out of the kiln, and the highest control temperature is 220 +/-10 ℃.

Compared with the prior art, the invention has the beneficial effects that: the aggregate of the magnesia-alumina brick is large-grained fused magnesia, and the fine powder is MgO fine powder and Al₂O₃Combination of materials such as micro powder, metal Al powder and the like, and MgO and Al in the high-temperature use process₂O₃The reaction in-situ synthesis of magnesia-alumina spinel has the permanent expansion rate of spinel and the stability of spinel to compensate the peeling off of magnesia grains caused by expansion, so that spinel layer is formed on the surface of the work layer to expand and block pores and to prevent slag from permeating and corroding, so that the product has high peeling and slag corrosion resistance during high temperature use, and the added metal aluminum powder or aluminum-magnesium alloy powder has antioxidant effect, and the magnesia-carbon brick is produced through mixing, forming and drying with phenolic resin as binding agent and carbon chain combining mode after drying treatment to form stable normal temperature physical and chemical indexes, simple production process, replacement of chromium containing refractory material, elimination of the harm of hexavalent chromium to human body and environment, and low porosity and high impact resistance, the high temperature is not easy to be oxidized.

Detailed Description

In order to make the technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following specific embodiments.

A carbon-free unburned magnesia-alumina brick comprises,

83-95 parts of fused magnesia;

3-10 parts of alumina powder;

1-4 parts of metal aluminum powder;

1-3 parts of phenolic resin.

As a further improvement of the invention, the fused magnesite is one or more of 96%, 97% and 98% of magnesium content.

As a further improvement of the invention, the particle size of the fused magnesia is one or a mixture of particle sizes of less than 0.088mm, 0.088-1mm, 1-3mm and 3-5 mm.

As a further improvement of the invention, the alumina powder is one or more of high-temperature alpha alumina micro powder, corundum fine powder and high-quality alumina fine powder.

As a further improvement of the invention, the particle size of the high-temperature alpha alumina micro powder is one or a mixture of more than 1 micron, 1-3 microns and 3-5 microns, the particle size of the corundum fine powder is less than 0.074mm, and the particle size of the high-quality bauxite fine powder is less than 0.074 mm.

As a further improvement of the invention, the metal aluminum powder is one or a combination of two of aluminum powder or aluminum magnesium alloy powder with the particle size of less than 0.074mm and the metal activity of more than 98 percent.

As a further improvement of the invention, the phenolic resin is a thermoplastic phenolic resin for refractory materials.

A preparation method of a carbon-free unburned magnesia-alumina brick comprises the following steps,

accurately metering the raw materials in proportion, and premixing the fused magnesia, alumina powder and metal aluminum powder;

secondly, adding the premix of the fused magnesia, the alumina powder and the metal aluminum powder into a pug mixer, mixing for 2-3 minutes, adding the phenolic resin, and continuing mixing for 8-10 minutes;

thirdly, the pug after mixing is beaten and formed on a brick press with proper mould and proper pressure to produce the required brick shape, and the brick shape is placed on a brick vehicle;

and (IV) pushing the formed brick blank vehicle into a tunnel drying kiln for drying for 24 hours, wherein the drying temperature is gradually pushed from the low-temperature region of the kiln inlet to the high-temperature region in the middle, then to the low-temperature region of the kiln outlet, and finally after 24 hours, the brick blank vehicle is taken out of the kiln, and the highest control temperature is 220 +/-10 ℃.

Example 1

The raw materials are added in the proportion: selecting fused magnesia with 96 percent of magnesium content, and screening 83 parts of fused magnesia with granularity less than 0.088mm and 3-5mm in equal parts; selecting 10 parts of high-temperature alpha alumina micro powder with the granularity less than 1 mu m; selecting 4 parts of aluminum powder with the granularity of less than 0.074mm and the metal activity of more than 98 percent; 3 parts of thermoplastic phenolic resin for refractory materials is selected.

Example 2

The raw materials are added in the proportion: selecting fused magnesia with the magnesium content of 98 percent, and screening 90 parts of fused magnesia with the granularity of less than 0.088mm, 0.088-1mm and 3-5mm in equal parts; selecting 6 parts of corundum fine powder with the granularity of less than 0.074mm and high-quality alumina fine powder with the granularity of less than 0.074mm in equal parts; selecting 2 parts of aluminum magnesium alloy powder with the granularity of less than 0.074mm and the metal activity of more than 98 percent; 2 parts of thermoplastic phenolic resin for refractory materials is selected.

Example 3

The raw materials are added in the proportion: selecting 97% of magnesium content, fused magnesite, and uniformly screening 92 parts of fused magnesite with four particle sizes of less than 0.088mm, 0.088-1mm, 1-3mm and 3-5 mm; selecting 3 parts of high-temperature alpha alumina micro powder with the granularity of 1-3 mu m, corundum fine powder with the granularity of less than 0.074mm and high-quality bauxite fine powder with the granularity of less than 0.074 mm; selecting 3 parts of equal parts of aluminum powder or aluminum-magnesium alloy powder with the granularity of less than 0.074mm and the metal activity of more than 98 percent; 2 parts of thermoplastic phenolic resin for refractory materials is selected.

The aggregate of the magnesia-alumina brick is large-grained fused magnesia, and the fine powder is MgO fine powder and Al₂O₃Powder, metal Al powder and other materials, and the product has no magnesia-alumina spinel and MgO and Al powder produced during high temperature use₂O₃The reaction is carried out to synthesize the magnesium aluminate spinel in situ, so that the energy consumption in the production process of the magnesium aluminate spinel is saved.

The production method of magnesia carbon brick using phenolic resin as binding agent, mixing, forming and drying is adopted, and after drying treatment, a carbon chain binding mode is formed, so that the normal-temperature physicochemical index of the product is stable, no separate carbon material is added in the product, about 1% -1.5% of residual carbon comes from the production of the phenolic resin after drying and carbonization, and the product has no carbon material, extremely low residual carbon component and can belong to the series of carbon-free bricks.

MgO and Al₂O₃The magnesium aluminate spinel is synthesized in situ in the high-temperature use process, so that the energy consumption in the production process of the magnesium aluminate spinel is saved, the magnesium aluminate spinel is not added into the product, and a small amount of magnesium aluminate spinel is synthesized in situ by magnesium oxide and aluminum oxide in the product in the high-temperature use process, so that the function of changing the product performance is achieved.

The excellent performance of the magnesia carbon brick lies in graphite carbon, and the serious peeling problem in the use process can cause the serious reduction of the service life of the product due to the large expansion coefficient of magnesia in the graphite-free carbon product, but in the invention, MgO and Al in fine powder in the high-temperature use process₂O₃The spinel is synthesized in situ in a solid phase manner, the permanent expansion rate of the spinel and the stability of the spinel compensate the peeling phenomenon of magnesia particles caused by expansion, a spinel layer is formed on the surface of a working layer, so that the product has better peeling resistance and slag corrosion resistance in the high-temperature use process, and the added metal aluminum powder or aluminum magnesium alloy powder has an antioxidation effect.